1. Field of Invention
The present invention is related to a method for identifying a movement of single tap on a touch device, particularly to an identifying method capable of resisting noise effectively and enhancing identification rate and a controller utilizing the method.
2. Brief Description of Related Art
The touch pad is a humanized input device in spite of the conventional input devices such as keyboard, mouse and locus ball being unable to satisfy need of the user. Further, a trend of designing electronic products is to pursue lightness, thinness, shortness and smallness so that it is not possible to integrate all kinds of input devices in a single electronic product. Because the touch pad can provide the user a humanized operation with handwriting input and has the function of the conventional input devices at the same time, the touch pad has become the most popular choice.
Referring to FIG. 1, the touch pad 10 can access analog/digital conversion and figure out coordinates of the touch point with a controller 20 after producing analog signals of voltage. Meanwhile, the controller 20 can identify if the user produce a single tap or click, double taps or clicks, a drag or a movement and then sends related control signal to a main unit 30 to control the cursor on a screen 40 of the main unit 30 accessing movements of shifting, selecting an item and executing a program.
The analog/digital converter (not shown) in the controller 20 can be interfered by foreign noise such as electromagnetic wave easily so that it is necessary to add proper samples and recognition algorithm in addition to requiring careful layout of internal circuit and increasing various filters for solving the problem. Otherwise, the noise is easy to result in phenomenon of temporary pseudo press or pseudo exit such that the controller 20 erroneously determines the movement.
U.S. Pat. No. 6,380,931 discloses an identifying method of single tap with a touch device and a brief summary thereof is described hereinafter. Referring FIG. 2, firstly, it is to detect if an object such as touch pen contacts the touch device as shown in step 201 and then it is to compare time T of the object with a default value Tmax and check if T is smaller than Tmax as shown in step 202. Further, it is to make sure if displacement S of the object on the touch device is smaller than a default value Smax as shown in step 203. In case of meeting the preceding two conditions, determination of single tap movement can be made and a control signal of representing the single tap and information regarding coordinates of position at the spot of clicking can be sent to the main unit. However, the preceding method is not possible to resist noise, which is apt to produce phenomenon of pseudo press. Especially in order to comply with calculation of the two restrictions (contact time and displacement), the set up cost of the logic circuit is expensive too.